1. Field of the Invention
The present invention relates to an image-processing computer system for a photogrammetric analytical measurement, in which a survey map is electronically produced based on a pair of photographed pictures obtained at two different photographing positions.
2. Description of the Related Art
For example, photogrammetry is carried out at a traffic accident spot. The traffic accident spot is photographed by an electronic still video digital camera in at least two different positions, and a survey map of the traffic accident spot is produced based on a pair of photographed pictures obtained at the different positions, as disclosed in, for example, Unexamined Japanese Patent Publications No.10-221072 and No.10-293026.
Before accurately scaled distances and lengths can be reproduced on the survey map, a standard measurement scale or target must be recorded together with the photographed objects in the pictures. The target is disclosed in, for example, Unexamined Japanese Patent Publications No.10-141951, No.10-170263, No.10-185562, No.10-185563, No.10-293026 and No.10-307025.
For the production of the survey map, a two-dimensional coordinate system is defined on each of the pictures, and two-dimensional positions of the objects, which are recorded on each picture, are determined by the two-dimensional coordinate system. Also, a three-dimensional coordinate system is defined on the target, and three-dimensional positions of the recorded objects are calculated based on the two-dimensional positions of the objects with respect to the three-dimensional coordinate system. Thus, it is possible to produce a survey map by projecting the three-dimensional coordinates, representing the objects, on one of the three planes defined by the three-dimensional system. Of course, the production of the survey map is performed using an image-processing computer system.
However, before the calculation of the three-dimensional positions of the recorded objects can be performed, it is necessary to determine camera parameters, by which the photographing position of the camera is represented with respect to the three-dimensional coordinate system.
Conventionally, the determination of the camera parameters is performed by correspondingly indicating reference points of the target on scenes of the pictures, displayed on a monitor, by clicking on them with the mouse. This manual indication of the reference points of the target is unreliable. Therefore, unless the manual indication is precisely performed, the determination of the camera parameters is inaccurate, and an accurate proper production of the survey map cannot be ensured.